GCN Circular 45892
Chenxi Bao (PKU), Zhuokai Liu (PKU), Yacheng Kang (PKU), and Yuhan Yao (PKU) report on behalf of the Interestar Collaboration and the PKU HiTF (High-energy Transients Follow-up) group:
We observed the field of EP261006a (Lao et al., GCN 45826; T0 = 2026-10-06T17:49:57) following its discovery and tentative classification as a TDE candidate (Eyles-Ferris et al., GCN 45831; Jiang et al., GCN 45833). Our observations were performed using two 28cm optical telescope operated by the Interestar Collaboration, one located in Chengde, China, and the other in Castillejar, Spain. Multiple epochs of Luminance-band imaging were obtained on 2026 October 7 and 9.
In our stacked difference images, we clearly detect the optical counterpart at a position consistent with that of AT 2026aetp (Eyles-Ferris et al., GCN 45831; Jiang et al., GCN 45833; Wu et al. GCN 45852; Bochenek et al., GCN 45853; Chen et al. GCN 45854; Zhang et al., GCN 45877; Bochenek et al., GCN 45883; Kang et al., GCN 45885). Reference images for the subtraction were constructed from Pan-STARRS g- and r-band imaging. Preliminary photometry was calibrated against nearby Pan-STARRS field stars and is reported on an approximate AB magnitude scale, without correction for Galactic extinction.
The Luminance-band observation log is summarized below:
| Date | Start_UT | T_mid - T0 (days) | Site | Exposure (s) | Magnitude (AB) |
|---|---|---|---|---|---|
| 2026-10-07 | 13:29:53 | 0.84 | Chengde | 2400 | 18.82 +/- 0.08 |
| 2026-10-07 | 14:17:18 | 0.88 | Chengde | 2700 | 18.83 +/- 0.07 |
| 2026-10-07 | 17:24:09 | 1.00 | Chengde | 2700 | 18.79 +/- 0.06 |
| 2026-10-07 | 18:18:05 | 1.04 | Chengde | 3000 | 18.78 +/- 0.06 |
| 2026-10-07 | 19:24:18 | 1.09 | Chengde | 3000 | 18.74 +/- 0.07 |
| 2026-10-09 | 20:33:05 | 3.13 | Castillejar | 3000 | 18.59 +/- 0.06 |
| 2026-10-09 | 21:30:35 | 3.17 | Castillejar | 2700 | 18.48 +/- 0.06 |
| 2026-10-09 | 22:18:08 | 3.20 | Castillejar | 3000 | 18.54 +/- 0.06 |
Our measurements indicate that the optical counterpart remained at approximately 18.8 mag on October 7 and appeared brighter on October 9. Further analysis and follow-up observations are ongoing.
As part of the PKU HiTF group, the Interestar Collaboration contributes to the rapid follow-up of high-energy transients.